Video Compressor — Shrink Any Video Without Uploading It
MediaVault compresses MP4, MOV, MKV and WebM files directly inside your browser tab. Your footage is read from disk into local memory, re-encoded by FFmpeg on your own CPU, and saved straight back to your downloads folder. Nothing is uploaded, queued, or stored on a server.
Why file size matters
Almost every platform enforces an upload ceiling, and phone cameras blow past it easily. A three-minute 4K clip from a recent iPhone routinely lands between 400MB and 900MB — far too big for email, Discord, or a Slack thread.
- Gmail and most mail servers cap attachments at 25MB
- Discord allows 8MB on the free tier and 25MB with Nitro Basic
- WhatsApp caps video sharing at 16MB
- Slack free workspaces stop at 1GB of total storage
How local compression works
The compressor loads FFmpeg compiled to WebAssembly and runs the same H.264 encoding pipeline a desktop app would. You choose a quality target, MediaVault picks the matching CRF and bitrate, and the encode happens in the tab. Because there is no upload leg, a 2GB source file starts compressing immediately instead of after a 2GB transfer.
What you keep by staying local
Cloud compressors ask you to hand unreleased footage, client work, or personal video to a third party whose terms usually permit storage and processing on their side. Local compression removes that question entirely.
- No upload wait, even on slow connections
- No watermark burned into your output
- No arbitrary file-size cap — your own memory is the limit
- Works on a plane, on hotel wifi, or fully offline after first load
How to use it
- Add your video. Open the compressor and drop in the file you want to shrink.
- Pick a quality target. Choose a compression preset — higher compression for messaging apps, lighter for archival quality.
- Compress and save. Run the compression and the smaller file downloads straight to your disk.
Frequently asked questions
Does compressing a video reduce its quality?
Some quality is always traded for size in a lossy codec, but at moderate settings the difference is hard to see on a phone or laptop screen. Start with a lighter preset and only increase compression if you still need a smaller file.
Is there a file size limit?
There is no server-side limit because there is no server involved. The practical ceiling is your device memory; multi-gigabyte files work on most modern laptops.
Will there be a watermark?
No. The output is exactly what FFmpeg produces, with no branding added.
Are my videos uploaded anywhere?
No. Files are read into browser memory and processed on your own CPU. No copy of your footage is transmitted.
Related tools
- Video Resizer — Reformat video to portrait, square or landscape for any platform.
- Video to GIF — Turn clips into looping GIFs with control over frame rate and size.